Pipe testing apparatus

ABSTRACT

Upper and lower axially spaced, radially expansible seals are secured to each other by an elongate spacer bar to form a pipe testing assembly. The assembly is positioned within the pipe to be tested and fluid pressure is employed to expand the upper and lower seals radially into sealing engagement with the surrounding pipe. Pressurized test fluid is introduced into the pipe within the enclosed area between the spaced seals to test the pipe for leaks. The lower seal includes a mandrel over which a preshaped cup seal is slidably disposed above a plurality of annular compression seals. The test fluid moves the cup seal downwardly which compresses the compression seals and causes them to move radially outwardly into sealing engagement with the surrounding pipe. Fluid containing chambers are formed between the expanded cup seal and compression seals to provide a back pressure which prevents high pressure collapse of the cup seal. If desired, a second seal having the same construction as the lower seal may be inverted and employed as the upper seal in the testing assembly. In a modified form, the preshaped cup seal is replaced by a normally retracted, annular working seal mounted on the mandrel which in turn is threadedly coupled with the lower end of the spacer bar. A friction drag holds the mandrel stationary and rotation of the spacer bar causes the upper end of the working seal to be moved outwardly by a cone spreader carried on the spacer bar whereupon the working seal functions in the same manner as the preformed cup seal of the preferred form. In its retracted position, the lower seal assembly has relatively small radial dimensions permitting it to be freely moved past constrictions within the pipe being tested and thereafter expanded into an operative cup shape by rotation of the spacer bar.

United States Patent [191 Miller [541 PIPE TESTING APPARATUS PrimaryExaminerLouis R. Prince Attorney-Carlos A. Torres, Bill B. Berryhill andTorres & Berryhill [57] ABSTRACT Upper and lower axially spaced,radially expansible seals are secured to each other by an elongatespacer bar to form a pipe testing assembly. The assembly is positionedwithin the pipe to be tested and fluid pressure is employed to expandthe upper and lower seals radially into sealing engagement with thesurrounding 1 Jan. 23, 1973 pipe. Pressurized test fluid is introducedinto the pipe within the enclosed area between the spaced seals to testthe pipe for leaks. The lower seal includes a mandrel over which apreshaped cup seal is slidably disposed above a plurality of annularcompression seals. The test fluid moves the cup seal downwardly whichcompresses the compression seals and causes them to move radiallyoutwardly into sealing engagement with the surrounding pipe. Fluidcontaining chambers are formed between the expanded cup seal andcompression seals to provide a back pressure which prevents highpressure collapse of the cup seal. If desired, a second seal having thesame construction as the lower seal may be inverted and employed as theupper seal in the testing assembly.

In a modified form, the preshaped cup seal is replaced by a normallyretracted, annular working seal mounted on the mandrel which in turn isthreadedly coupled with the lower end of the spacer bar. A friction dragholds the mandrel stationary and rotation of the spacer bar causes theupper end of the working seal to be moved outwardly by a cone spreadercarried on the spacer bar whereupon the working seal functions in thesame manner as the preformed cup seal of the preferred form. In itsretracted position, the lower seal assembly has relatively small radialdimensionspermitting it to be freely moved past constrictions within thepipe being tested and thereafter expanded into an operative cup shape byrotation of the spacer bar.

10 Claims, 6 Drawing Figures PIPE TESTING APPARATUS BACKGROUND OF THEINVENTION The tubing strings, pipe lines, drill pipe and other conduitscommonly associated with the production and transportation of oil andgas are often required to carry liquids and gas fluids which are underextremely high pressures, often as high as 15,000 psi or more. In orderto avoid destructive and dangerous loss of oil and gas, such conduitsare customarily tested for leakage and structural integrity before beingput in use. Initially, each pipe section is normally inspected at theplace where it is manufactured. Because of the danger of damage duringtransportation, the section is again tested before being placed in thewell. Where pipe previously disposed in a well is removed and replaced,the replaced pipe is normally testedv before being reused.

The devices and techniques employed in the testing ofwell pipe areextremely varied. Some ofsuch devices are limited to testing for leakageat the joint between two mating sections while others test not only thejoint but also the intermediate bodies between the joint. Many commonlyemployed testing devices test the pipe as it is being lowered into thewell bore by creatin-gan internal hydraulic pressure between axiallyspaced seals set within the pipe. The internal pressure is monitored fora short period and any decrease in the pressure is indicative of a leak.This technique is generally referred to as hydrostatic pipe testing.

The lower seal in hydrostatic pipe testing devicesis normally set byhydraulic pressure which is communicated to the'lower seal through abore formed in the connecting bar extendingbetween the upper and lowerseals. The hydraulic pressure is employed to move a piston in anexpansion chamber which in turn compresses an annular, elastomeric sealcausing the seal to move radially outwardly into sealing engagement withthe surrounding pipe. The upper seal in such devices is normally set insubstantially the same manner.

Setting devices which employ hydraulically actuated expansion chambersare normally expensive and difficult to maintain because ofthc finetolerances and extensive machine work normally required in themanufacture' and operation of such devices. Moreover, the lowerexpansion chamber in aconventional hydrostatic test tools must besupplied with high pressure fluid which is communicatedjto the chamberthrough a bore extending the length of the spacer bar which connects theupper and lower seals. In many cases, the connecting spacer bar isconstructed in several mating sections to form a total length ofapproximately 90 feet. The cost of machining bores through the rodsrequired to form spacer bars of this length are relatively high and therods must be made ,ofhigh quality, expensive alloys to withstand thehigh pressures encountered during the testing operation.

SUMMARY OF THE INVENTION The apparatus of the present invention includesupper and lower axially spaced seals with the lower seal being set byfluid injected directly into the pipe in the area between the two spacedseals. By this means, the need for a central bore extending along thelength of the connecting spacer bar structure is eliminated.

The bottom tool includes an upwardly facing cup seal which is drivendownwardly by the testing fluid to compress and radially expand theannular compression seals. The expansion of the compression seals forcesthem into sealing engagement with the surrounding well'pipe. Compressedfluid trapped between the annular seals and the. cup seal in pluralfluid chambers provides a support to the cup seal which prevents it fromcollapsing under extremely high pressures.

The combination of a cup seal and annular compression seals in the testtool assembly provides for a lowcost, easily operated and easilymaintained apparatus which may be set with fluid pressure exerted in theannular area between the spacer bar and the surrounding pipe walls. lnaddition, where liquid test fluid is used, the lower cup seal retainsthe pressurizing liquid between each successive test to eliminate theneed for completely refilling the entire pipe between the two sealsbetween successive tests. The retention of the testing fluids alsoprevents dilution of well fluids and reduces the quantity of fluidrequired to perform the entire test. The top seal in the apparatus may,if desired, be formed from a tool constructed in the same manner as thebottom tool but inverted so that the mouth section of the cup seal isdirected downwardly.

The combined use of cup seals and annular compression seals permits theuse of a smaller, more resilient cup seal to be employed in the assemblywhich thereby permits the tools to be easily moved past internalrestrictions formed within the pipe being tested. The increased pressurecapability of the device is attributable to the formation of the fluidcontaining chambers upon the radial expansion of the annular seal rings.Trapped fluid in the chambers provides back pressure to the cup sealwhich prevents even relatively small, resilient cup seals fromcollapsing under the pressure of the testing fluid.

The cup seal and annular compression seals are assembled in a simple,direct manner over a single piece mandrel which contributes to lowmanufacturing costs, simplicity of operation and ease of maintenance.

In a modified form of the invention, an annular working seal positionedat the top of the seal assembly is adapted to be expanded radiallyoutwardly into sealing engagement with the surrounding pipe wall. Beforeradial expansion, the working seal closely surrounds the supportingmandrel to provide a composite seal assembly which has relatively smallradial dimensions to permit the tool to be freely moved throughrestrictions formed in the pipe under test. Once the non-expanded sealhas been lowered below a restriction, rotation of the spacer bar causesa cone spreader to move into engagement with the working seal. The conespreader causes the working seal to expand radially outwardly into theshape of a conventional cup seal until it engages the pipe wallwhereupon the lower seal assembly functions in the manner previouslydescribed for the preferred form of the invention. After the test hasbeen completed, the spacer bar is rotated in the opposite directionpermitting the working seal to retract inwardly so that the assembly maybe removed from the pipe.

The foregoing features and advantages of the present invention as wellas others may be better understood by reference to the followingspecification, drawings and the related claims.

BRlEF DESCRlPTlON OF THE DRAWINGS FIG. 1 is an elevation, partly insection, illustrating the pipe testing apparatus of the presentinvention in operative position with a pipe which is to be tested;

FlG. 2 is an elevation of the lower test tool of the apparatus of thepresent invention;

FIG. 3 is an elevation, partially in section, illustrating the lowertest tool of the present invention in its set position within asurrounding well pipe;

FIG. 4 is a vertical section, on an enlarged scale, illustrating thebottom test tool of the present invention in its unset condition;

FIG. 5 is an elevation, partially in section illustrating a modified,mechanically expandable form of the present invention; and

FIG. 6 is a vertical section showing the modified form of the tool inits partially expanded unsetposition.

DESCRIPTION OF THE PREFERRED EMBODlMENTS Referring to HO. 1, a preferredform of the apparatus of the present invention is indicated generally at10 as it appears when positioned within a well conduit C which is to betested for leaks and structural strength. The test assembly 10 includesan upper test tool 11, a lower test tool 12 and a connecting spacer bar13. The spacer bar 13 is made up of a plurality of connecting rods 13a,13b and 130 to provide the desired axial spacing between the upper andlower test tools.

In conducting the test on the conduit C, a suitable testing fluid suchas water is introduced into an annular area A formed between the spacerbar 13 and the surrounding walls of the conduit C. The test fluid may beintroduced into the annular area A by means of a supply line L connectedthrough a head assembly H which channels fluid supplied by the linethrough the upper seal 11 where it is injected into the annular area Athrough an exhaust bore 13a. The head assembly H is conventional and itwill be understood that any suitable means for introducing the testfluid into the annular area A may be employed with the apparatus 10.

When the annular area A has been fllled with the test fluid, the fluidis pressurized to a predetermined value and a pressure sensitive monitor(not shown) is employed to detect any loss of pressure to indicate thepresence of leakage in the walls of the conduit C or at the joints atmating sections forming the conduit C.

It will be appreciated that the upper and lower seals 11 and 12,respectively, must provide a leakproof engagement with the surroundingwalls of the conduit C which is sufficient to withstand the highpressures employed in the testing fluid filling the annular area A. Inthe pipe testing apparatus 10, the fluid pressure employed in testingthe pipe section C is also employed to set the lower test tool 11causing it to move into firm sealing engagement with the surroundingconduit walls.

Referring jointly to FIGS. 2, 3 and 4, it may be seen that the lowertest tool 12 includes a central mandrel 14 which is threadedly engagedat its upper end with the spacer bar rod 13c. The mandrel 14 carries aseal means having an upper preformed cup seal section 15. The basesection of the seal 15 is carried in a concave seat formed at the upperend of a cup mount 16. The resilient cup seal 15 and metallic,non-yieldable cup mount 16 are positioned above a compression sealassembly including three metallic spacer rings 17, 18 and 19 spacedabout dual resilient compression ring seals 20 and 21.

The upper end of the tool 12 includes an adapter member 22 designed tosecure the mandrel 14 to the lower end of the spacer rod 13c. A mountingsleeve 23 is positioned between the body of the mandrel 14 and theinternal bore of the cup seal 15 to retain the cup seal in firm sealingengagement with the upper end of the cup mount 16. Resilient O-ringseals 24 and 25 are formed internally of the cup mount 16 to provide acontinuous, sliding seal between the cup mount and the underlyingmandrel 14.

In operation, the lower test tool 12 is set by the testing fluidinjected into the annular area A. The seal 15 includes an upper mouthsection 15a which is in sealing engagement with the surrounding wall ofthe conduit C at all times. The test fluid in the annular area A actsagainst the mouth section 15a causing it to move radially outwardly intotight sealing engagement with the surrounding wall and simultaneouslytending to exert a downwardly directed force on the seal. A base section15b formed at the lower portion of the cup seal 15 sealingly engages theunderlying mandrel l4 and cooperates with the annular seals 24 and 25 inthe cup mount 16 to form a continuous fluid seal in the conduit C.Increasing pressure in the annular area A acts against the cup seal 15causing it to move downwardly with respect to the relatively stationarymandrel 14. This downward motion and attendant force is transmitted bythe cup mount 16 to the lower compression seal assembly. As the cupmount 16 is moved downwardly over the mandrel, the resilient compressionseals 20 and 21 are foreshortened axially between the base of the cupmount and an upper retaining shoulder formed near the bottom portion ofthe mandrel 14.

As the rings 20 and 21 are foreshortened axially, they expand radiallyinto engagement with the surrounding walls of the conduit C asillustrated in FIG. 3. In its expanded position, the tool 12 forms twofluid containing chambers A, and A Where the testing fluid is a liquid,the fluid contained in the areas A and A resist compressions andprovides a support to the cup seal 15 permitting it to withstandrelatively high fluid pressures in the testing annulus A. The formationof plural fluid containing chambers as illustrated, assists in reducingthe extent of axial travel of the cup 15 on the mandrel to provide thedesired high pressure strength. When pressure in the annulus A isreduced, the sealing engagement of the compression rings 20 and 21 isautomatically terminated.

Between each test, the normally expanded cup 15 retains the liquid inthe annular area A to eliminate the need for refilling the area eachtime a new section of conduit is to be tested. By this means, the timerequired to complete an entire test may be substantially decreased andthe amount of water or other fluid required in completing the test canbe substantially reduced. If desired, the upper test tool 11 may be ofsimilar construction to the test tool 12 but reversed in position sothat the high pressure fluid in the annular area A tends to drive thecompression seal assembly upwardly over the supporting mandrel. ltshould, however, be understood that either the upper orlower test toolmay be employed in combination with any suitable mechanism for providingthe desired seal of the well conduit.

Referring to FIGS. 5 and 6, a modified form of the test tool isindicated generally at 110. The tool 110 includes a mandrel 114 which isthreadedly secured by means of threads 1l4b formed at its upper end to aspreader cone member having a conical spreading surface 1132 and centralinternal threads 113f adapted to mate with the mandrel threads 114b. Anannular working seal 115 is carried over the mandrel 114 in the mannerillustrated in FIG. 5. The seal 115 is the uppermost seal in a sealassembly which includes a force transmitting ring 116 formed of metaland two resilient annular compression seals 120 and 121 separated by ametallic spacer ring 118. The tool 110 is completed by resilient dragspring members l14b which are adapted to engage the surrounding walls ofthe conduit C to hold the mandrel stationary with respect to theconduit.

In operation, the tester 110 is lowered into position within the conduitC and when the desired subsurface location has been reached, the spacerbar 113 is rotated to advance the internal threads ll3f over the uppermandrel threads 114b, During rotation of the spacer bar 113, the dragsprings 114b frictionally engage the surrounding wall of the conduit Cto hold the mandrel stationary. Rotation of the threads 1l3f about themandrel threads 1141: moves the conical spreading surface 113edownwardly with respect to the working seal 113.

As best illustrated in FIG. 6, downward movement of the conical surfacell3e forces the mouth portion of the working seal radially outwardlyinto engagement with the surrounding walls of the conduit C. Once theseal 115 has engaged the pipe wall, the seal functions-in the samemanner as previously described for the conventional, preformed cup sealof the preferred embodiment wherein fluid pressure in the annular area Amoves the cup seal downwardly thereby compressing the two annularcompression rings and moving them into sealing engagement with thesurrounding pipe wall. After the test has been completed, the directionof rotation of the spacer bar 113 is reversed causing the spreadersurface 113e to move away from the resilient seal 115 thereby permittingit to retract radiallyinwardly. While the embodiment of'FlGS. 5 and 6may be employed in any conduit, it will be understood that it isespecially advantageous where restrictions formed within the conduitrequirethe use ofa tool having relatively small radial dimensions.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof, and various changes in the size,shape andmaterials as well as in the details of'the. illustratedconstruction may be made within the scope of the appended claims withoutdeparting from the spirit ofthe invention.

What is claimed is:

l. A test tool adapted to be positioned in a tubular well pipecomprising: I

a. an axially extending mandrel means having upper and lower axiallyspaced ends;

b. lower seal means including resilient cup seal means having basesection means slidably and sealingly carried on said mandrel means andmouth section means adapted to open upwardly to slidably engage theinternal walls of said tubular well pipe for forming a seal between saidmandrel means and said well pipe;

c. radially expansible, resilient compression seal means carried on saidmandrel means and adapted to expand radially into sealing engagementwith said well pipe when foreshortened axially for forming a sealbetween said mandrel means and said well pipe;

d. retaining means connected with said lower end of said mandrel meansfor forming a lower retaining base for said compression seal means;

e. non-resilient force transmitting means slidingly and sealinglycarried on said mandrel means between said cup seal means and saidcompression seal means for transmitting downward axial movement'of saidcup seal means to said compression seal means whereby said compressionseal means is foreshortened axially between said force transmittingmeans and said retainingmeans;

f. axially extending spacer bar means having upper and lower axiallyspaced ends with said lower bar means end secured to said upper mandrelend;

g. upper seal means connected with said upper bar means end and adaptedto sealingly engage the pipe wall to form a seal between said bar meansand said pipe wall;

h. fluid injection means for injecting a pressurized liquid or gas fluidinto the annular area between said bar means and said well pipe in thearea between upper and lower seal means; and

. means to force said mouth section means into sealing engagementwith'the internal walls of said tubular pipe, said pressurized fluidwithin said annular area forcing said cup seal means against saidnon-resilient force transmitting means to foreshor-' ten axially saidcompression seal means and thereby cause it to expand radially into itssealing engagement with said well pipe.

2. A test tool as defined in claim 1 wherein said lower seal meansfurther includes fluid chamber forming means for producing a pluralityof annular, fluid filled chambers between said lower seal means and saidwell pipe.

3. A test tool as defined in claim 2 wherein said fluid chamber formingmeans includes a plurality of annular, expansible elastomeric ringsseparated axially from each other by non-expansible spacer means.

4. A test tool as defined in claim 1 wherein said cup seal meansincludes expander means for expanding said mouth section means radiallyoutwardly into sealing engagement with the internal pipe walls.

5. A test tool as defined in claim 4 wherein said expander meansincludes spreader means having a conical surface adapted to movedownwardly with respect to said mandrel means and said cup seal meanswhereby said conical surface advances between said mandrel means andsaid cup seal means causing said cup seal means to be forced radiallyoutwardly into sealing engagement with the internal pipe walls.

6. A test tool as defined in claim wherein:

a. said conical spreading surface is fixed with respect to said spacerbar means;

b. said mandrel means is threadedly engaged with said spacer bar means;and

c. said mandrel means includes friction producing drag means slidablyengaging the internal pipe walls for holding said mandrel meansstationary with respect to said pipe whereby rotation of said spacer barmeans moves said conical spreading surface toward or away from said cupseal means causing said cup seal to radially expand or retract dependingupon the direction of rotation of said spacer bar means.

7. A test tool as defined in claim 3 wherein said cup seal meansincludes expander means for expanding said mouth section means radiallyoutwardly into sealing engagement with the internal pipe walls.

8. A test tool as defined in claim 7 wherein said expander meansincludes spreader means having a conical surface adapted to movedownwardly with respect to said mandrel means and said cup seal meanswhereby said conical surface advances between said mandrel means andsaid cup seal means causing said cup seal means to be forced radiallyoutwardly into sealing engagement with the internal pipe walls.

9. A test tool as defined in claim 8 wherein:

a. said conical spreading surface is fixed with respect to said spacerbar means;

b. said mandrel means is threadedly engaged with said spacer bar means;and

c. said mandrel means includes friction producing drag means slidablyengaging the internal pipe walls for holding said mandrel meansstationary with respect to said pipe whereby rotation of said spacer barmeans moves said conical spreading surface toward or away from said cupseal means causing said cup seal to expand or retract depending upon thedirection of rotation of said spacer bar means.

10. A test tool as defined in claim 1 wherein said means to force saidmouth section means into sealing engagement with the internal walls ofsaid tubular pipe comprises said pressurized fluid in said annular area.

1. A test tool adapted to be positioned in a tubular well pipe comprising: a. an axially extending mandrel means having upper and lower axially spaced ends; b. lower seal means including resilient cup seal means having base section means slidably and sealingly carried on said mandrel means and mouth section means adapted to open upwardly to slidably engage the internal walls of said tubular well pipe for forming a seal between said mandrel means and said well pipe; c. radially expansible, resilient compression seal means carried on said mandrel means and adapted to expand radially into sealing engagement with said well pipe when foreshortened axially for forming a seal between said mandrel means and said well pipe; d. retaining means connected with said lower end of said mandrel means for forming a lower retaining base for said compression seal means; E. non-resilient force transmitting means slidingly and sealingly carried on said mandrel means between said cup seal means and said compression seal means for transmitting downward axial movement of said cup seal means to said compression seal means whereby said compression seal means is foreshortened axially between said force transmitting means and said retaining means; f. axially extending spacer bar means having upper and lower axially spaced ends with said lower bar means end secured to said upper mandrel end; g. upper seal means connected with said upper bar means end and adapted to sealingly engage the pipe wall to form a seal between said bar means and said pipe wall; h. fluid injection means for injecting a pressurized liquid or gas fluid into the annular area between said bar means and said well pipe in the area between said upper and lower seal means; and i. means to force said mouth section means into sealing engagement with the internal walls of said tubular pipe, said pressurized fluid within said annular area forcing said cup seal means against said non-resilient force transmitting means to foreshorten axially said compression seal means and thereby cause it to expand radially into its sealing engagement with said well pipe.
 2. A test tool as defined in claim 1 wherein said lower seal means further includes fluid chamber forming means for producing a plurality of annular, fluid filled chambers between said lower seal means and said well pipe.
 3. A test tool as defined in claim 2 wherein said fluid chamber forming means includes a plurality of annular, expansible elastomeric rings separated axially from each other by non-expansible spacer means.
 4. A test tool as defined in claim 1 wherein said cup seal means includes expander means for expanding said mouth section means radially outwardly into sealing engagement with the internal pipe walls.
 5. A test tool as defined in claim 4 wherein said expander means includes spreader means having a conical surface adapted to move downwardly with respect to said mandrel means and said cup seal means whereby said conical surface advances between said mandrel means and said cup seal means causing said cup seal means to be forced radially outwardly into sealing engagement with the internal pipe walls.
 6. A test tool as defined in claim 5 wherein: a. said conical spreading surface is fixed with respect to said spacer bar means; b. said mandrel means is threadedly engaged with said spacer bar means; and c. said mandrel means includes friction producing drag means slidably engaging the internal pipe walls for holding said mandrel means stationary with respect to said pipe whereby rotation of said spacer bar means moves said conical spreading surface toward or away from said cup seal means causing said cup seal to radially expand or retract depending upon the direction of rotation of said spacer bar means.
 7. A test tool as defined in claim 3 wherein said cup seal means includes expander means for expanding said mouth section means radially outwardly into sealing engagement with the internal pipe walls.
 8. A test tool as defined in claim 7 wherein said expander means includes spreader means having a conical surface adapted to move downwardly with respect to said mandrel means and said cup seal means whereby said conical surface advances between said mandrel means and said cup seal means causing said cup seal means to be forced radially outwardly into sealing engagement with the internal pipe walls.
 9. A test tool as defined in claim 8 wherein: a. said conical spreading surface is fixed with respect to said spacer bar means; b. said mandrel means is threadedly engaged with said spacer bar means; and c. said mandrel means includes friction producing drag means slidably engaging the internal pipe walls for holding said mandrel means stationary with respect to said pipe whereby rotation of said spacer bar means moves said conical spreading surface toward or aWay from said cup seal means causing said cup seal to expand or retract depending upon the direction of rotation of said spacer bar means.
 10. A test tool as defined in claim 1 wherein said means to force said mouth section means into sealing engagement with the internal walls of said tubular pipe comprises said pressurized fluid in said annular area. 